From prior art, for example from Document EP 0 966 376 B1, it is known to monitor the application and release of tension on the brake cable in motor vehicle parking brakes, in particular in electronically controlled parking brakes that have an electromechanical drive. To this end a force measurement is implemented to detect the force applied to the brake cable and a distance measurement is implemented to detect adjustment travel of the brake cable already covered. This requires both a sensor system to measure the force and also a further sensor system to measure the distance.
For force measurement, a force sensor is disposed in or on the actuating cable for the direct detection of the force applied to the actuating cable. The distance is measured by means of a displacement sensor assigned to the actuating cable, the signals of said displacement sensor being fed to the control device as input variables. In this way, the sensor signals from two sensor units that are at different positions of the brake cable and hence remote therefrom, even possibly outside the actual drive unit and separate from the control unit, must be brought together to the evaluating unit located in the control unit, for example a processor. Complicating the matter is the fact that the sensor units must move along with the stroke of the actuating cable. This requires additional signal lines and costly circuit work, such as, for example, the laying of flexible lines or flexible line carriers.